Understanding Psychology (10th Ed)

Applying Psychology 
in the 21st Century
Trucks and Dolls: Does Fetal 
Exposure to Testosterone 
Aff ect How Children Play?
In one case, the stereotypes are true: Boys 
typically like rough-and-tumble play and 
their toys of choice are cars and trucks, 
whereas girls prefer quieter activities and 
like to play with dolls. What is less clear is 
why these gender differences occur. Are 
they biological like sex itself, or are they 
learned as a consequence of how we treat 
boys and girls differently in society?
This question may never be answered 
conclusively. It’s almost certainly the case 
that some combination of biological and 
environmental factors is at work. Recent 
research provides strong evidence for the 
importance of biological factors: It seems 
that the male hormone testosterone plays 
an important role in determining juvenile 
play behavior (Hines et al., 2002; Pasterski 
et al., 2005).
In a recent large-scale study, researchers 
measured the concentration of testosterone 
in the amniotic fl uid of more than 200 male 
and female fetuses as part of a long-term 
study on the effects of fetal testosterone on 
development. (Although testosterone is the 
primary androgen, or male sex hormone, it 
also is found to a lesser extent in females.)
Eight years later, when the children 
were in middle childhood, researchers 
gave their parents a questionnaire about 
the children’s play behavior. The results 
were clear: There was a strong relationship 
between prenatal testosterone concentra-
tion and how their children played; higher 
concentrations of fetal testosterone pre-
dicted more male-typical play behaviors 
in both boys and girls (Auyeung et al., 
2009).
One interesting aspect of this study is 
that the infl uence of fetal testosterone on 
male-typical play was found in both 
genders—that is, higher levels of testoster-
one produced more boyish kinds of play in 
both boys and girls. Another interesting 
aspect is that these children were not un-
usual in any way. For instance, they were 
not exposed to unnaturally high levels of 
prenatal hormones through drug use or dis-
ease. They merely experienced normal vari-
ation in the presence of fetal testosterone. 
That leaves few alternative explanations to 
account for the differences in their play be-
havior that emerged later in development.
• Could conformity pressures on boys and girls during middle childhood lead chil-
dren to behave in more stereotypically “male” and “female” ways?
• What should parents do, if anything, to affect the degree to which their children 
behave in ways that are consistent with stereotypes about male and female behavior?
RETHINK
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